Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 890 insertions, 0 deletions

diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
new file mode 100644
index 000000000..b767a38a7
--- /dev/null
+++ b/lib/test_rhashtable.c
@@ -0,0 +1,890 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Resizable, Scalable, Concurrent Hash Table
+ *
+ * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
+ * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
+ */
+
+/**************************************************************************
+ * Self Test
+ **************************************************************************/
+
+#include <linux/init.h>
+#include <linux/jhash.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/rcupdate.h>
+#include <linux/rcupdate_wait.h>
+#include <linux/rhashtable.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/random.h>
+#include <linux/vmalloc.h>
+#include <linux/wait.h>
+
+#define MAX_ENTRIES	1000000
+#define TEST_INSERT_FAIL INT_MAX
+
+static int parm_entries = 50000;
+module_param(parm_entries, int, 0);
+MODULE_PARM_DESC(parm_entries, "Number of entries to add (default: 50000)");
+
+static int runs = 4;
+module_param(runs, int, 0);
+MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");
+
+static int max_size = 0;
+module_param(max_size, int, 0);
+MODULE_PARM_DESC(max_size, "Maximum table size (default: calculated)");
+
+static bool shrinking = false;
+module_param(shrinking, bool, 0);
+MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");
+
+static int size = 8;
+module_param(size, int, 0);
+MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");
+
+static int tcount = 10;
+module_param(tcount, int, 0);
+MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");
+
+static bool enomem_retry = false;
+module_param(enomem_retry, bool, 0);
+MODULE_PARM_DESC(enomem_retry, "Retry insert even if -ENOMEM was returned (default: off)");
+
+struct test_obj_val {
+	int	id;
+	int	tid;
+};
+
+struct test_obj {
+	struct test_obj_val	value;
+	struct rhash_head	node;
+};
+
+struct test_obj_rhl {
+	struct test_obj_val	value;
+	struct rhlist_head	list_node;
+};
+
+struct thread_data {
+	unsigned int entries;
+	int id;
+	struct task_struct *task;
+	struct test_obj *objs;
+};
+
+static u32 my_hashfn(const void *data, u32 len, u32 seed)
+{
+	const struct test_obj_rhl *obj = data;
+
+	return (obj->value.id % 10);
+}
+
+static int my_cmpfn(struct rhashtable_compare_arg *arg, const void *obj)
+{
+	const struct test_obj_rhl *test_obj = obj;
+	const struct test_obj_val *val = arg->key;
+
+	return test_obj->value.id - val->id;
+}
+
+static struct rhashtable_params test_rht_params = {
+	.head_offset = offsetof(struct test_obj, node),
+	.key_offset = offsetof(struct test_obj, value),
+	.key_len = sizeof(struct test_obj_val),
+	.hashfn = jhash,
+};
+
+static struct rhashtable_params test_rht_params_dup = {
+	.head_offset = offsetof(struct test_obj_rhl, list_node),
+	.key_offset = offsetof(struct test_obj_rhl, value),
+	.key_len = sizeof(struct test_obj_val),
+	.hashfn = jhash,
+	.obj_hashfn = my_hashfn,
+	.obj_cmpfn = my_cmpfn,
+	.nelem_hint = 128,
+	.automatic_shrinking = false,
+};
+
+static atomic_t startup_count;
+static DECLARE_WAIT_QUEUE_HEAD(startup_wait);
+
+static int insert_retry(struct rhashtable *ht, struct test_obj *obj,
+                        const struct rhashtable_params params)
+{
+	int err, retries = -1, enomem_retries = 0;
+
+	do {
+		retries++;
+		cond_resched();
+		err = rhashtable_insert_fast(ht, &obj->node, params);
+		if (err == -ENOMEM && enomem_retry) {
+			enomem_retries++;
+			err = -EBUSY;
+		}
+	} while (err == -EBUSY);
+
+	if (enomem_retries)
+		pr_info(" %u insertions retried after -ENOMEM\n",
+			enomem_retries);
+
+	return err ? : retries;
+}
+
+static int __init test_rht_lookup(struct rhashtable *ht, struct test_obj *array,
+				  unsigned int entries)
+{
+	unsigned int i;
+
+	for (i = 0; i < entries; i++) {
+		struct test_obj *obj;
+		bool expected = !(i % 2);
+		struct test_obj_val key = {
+			.id = i,
+		};
+
+		if (array[i / 2].value.id == TEST_INSERT_FAIL)
+			expected = false;
+
+		obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
+
+		if (expected && !obj) {
+			pr_warn("Test failed: Could not find key %u\n", key.id);
+			return -ENOENT;
+		} else if (!expected && obj) {
+			pr_warn("Test failed: Unexpected entry found for key %u\n",
+				key.id);
+			return -EEXIST;
+		} else if (expected && obj) {
+			if (obj->value.id != i) {
+				pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
+					obj->value.id, i);
+				return -EINVAL;
+			}
+		}
+
+		cond_resched_rcu();
+	}
+
+	return 0;
+}
+
+static void test_bucket_stats(struct rhashtable *ht, unsigned int entries)
+{
+	unsigned int total = 0, chain_len = 0;
+	struct rhashtable_iter hti;
+	struct rhash_head *pos;
+
+	rhashtable_walk_enter(ht, &hti);
+	rhashtable_walk_start(&hti);
+
+	while ((pos = rhashtable_walk_next(&hti))) {
+		if (PTR_ERR(pos) == -EAGAIN) {
+			pr_info("Info: encountered resize\n");
+			chain_len++;
+			continue;
+		} else if (IS_ERR(pos)) {
+			pr_warn("Test failed: rhashtable_walk_next() error: %ld\n",
+				PTR_ERR(pos));
+			break;
+		}
+
+		total++;
+	}
+
+	rhashtable_walk_stop(&hti);
+	rhashtable_walk_exit(&hti);
+
+	pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u\n",
+		total, atomic_read(&ht->nelems), entries, chain_len);
+
+	if (total != atomic_read(&ht->nelems) || total != entries)
+		pr_warn("Test failed: Total count mismatch ^^^");
+}
+
+static s64 __init test_rhashtable(struct rhashtable *ht, struct test_obj *array,
+				  unsigned int entries)
+{
+	struct test_obj *obj;
+	int err;
+	unsigned int i, insert_retries = 0;
+	s64 start, end;
+
+	/*
+	 * Insertion Test:
+	 * Insert entries into table with all keys even numbers
+	 */
+	pr_info("  Adding %d keys\n", entries);
+	start = ktime_get_ns();
+	for (i = 0; i < entries; i++) {
+		struct test_obj *obj = &array[i];
+
+		obj->value.id = i * 2;
+		err = insert_retry(ht, obj, test_rht_params);
+		if (err > 0)
+			insert_retries += err;
+		else if (err)
+			return err;
+	}
+
+	if (insert_retries)
+		pr_info("  %u insertions retried due to memory pressure\n",
+			insert_retries);
+
+	test_bucket_stats(ht, entries);
+	rcu_read_lock();
+	test_rht_lookup(ht, array, entries);
+	rcu_read_unlock();
+
+	test_bucket_stats(ht, entries);
+
+	pr_info("  Deleting %d keys\n", entries);
+	for (i = 0; i < entries; i++) {
+		struct test_obj_val key = {
+			.id = i * 2,
+		};
+
+		if (array[i].value.id != TEST_INSERT_FAIL) {
+			obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
+			BUG_ON(!obj);
+
+			rhashtable_remove_fast(ht, &obj->node, test_rht_params);
+		}
+
+		cond_resched();
+	}
+
+	end = ktime_get_ns();
+	pr_info("  Duration of test: %lld ns\n", end - start);
+
+	return end - start;
+}
+
+static struct rhashtable ht;
+static struct rhltable rhlt;
+
+static int __init test_rhltable(unsigned int entries)
+{
+	struct test_obj_rhl *rhl_test_objects;
+	unsigned long *obj_in_table;
+	unsigned int i, j, k;
+	int ret, err;
+
+	if (entries == 0)
+		entries = 1;
+
+	rhl_test_objects = vzalloc(array_size(entries,
+					      sizeof(*rhl_test_objects)));
+	if (!rhl_test_objects)
+		return -ENOMEM;
+
+	ret = -ENOMEM;
+	obj_in_table = vzalloc(array_size(sizeof(unsigned long),
+					  BITS_TO_LONGS(entries)));
+	if (!obj_in_table)
+		goto out_free;
+
+	err = rhltable_init(&rhlt, &test_rht_params);
+	if (WARN_ON(err))
+		goto out_free;
+
+	k = get_random_u32();
+	ret = 0;
+	for (i = 0; i < entries; i++) {
+		rhl_test_objects[i].value.id = k;
+		err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node,
+				      test_rht_params);
+		if (WARN(err, "error %d on element %d\n", err, i))
+			break;
+		if (err == 0)
+			set_bit(i, obj_in_table);
+	}
+
+	if (err)
+		ret = err;
+
+	pr_info("test %d add/delete pairs into rhlist\n", entries);
+	for (i = 0; i < entries; i++) {
+		struct rhlist_head *h, *pos;
+		struct test_obj_rhl *obj;
+		struct test_obj_val key = {
+			.id = k,
+		};
+		bool found;
+
+		rcu_read_lock();
+		h = rhltable_lookup(&rhlt, &key, test_rht_params);
+		if (WARN(!h, "key not found during iteration %d of %d", i, entries)) {
+			rcu_read_unlock();
+			break;
+		}
+
+		if (i) {
+			j = i - 1;
+			rhl_for_each_entry_rcu(obj, pos, h, list_node) {
+				if (WARN(pos == &rhl_test_objects[j].list_node, "old element found, should be gone"))
+					break;
+			}
+		}
+
+		cond_resched_rcu();
+
+		found = false;
+
+		rhl_for_each_entry_rcu(obj, pos, h, list_node) {
+			if (pos == &rhl_test_objects[i].list_node) {
+				found = true;
+				break;
+			}
+		}
+
+		rcu_read_unlock();
+
+		if (WARN(!found, "element %d not found", i))
+			break;
+
+		err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+		WARN(err, "rhltable_remove: err %d for iteration %d\n", err, i);
+		if (err == 0)
+			clear_bit(i, obj_in_table);
+	}
+
+	if (ret == 0 && err)
+		ret = err;
+
+	for (i = 0; i < entries; i++) {
+		WARN(test_bit(i, obj_in_table), "elem %d allegedly still present", i);
+
+		err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node,
+				      test_rht_params);
+		if (WARN(err, "error %d on element %d\n", err, i))
+			break;
+		if (err == 0)
+			set_bit(i, obj_in_table);
+	}
+
+	pr_info("test %d random rhlist add/delete operations\n", entries);
+	for (j = 0; j < entries; j++) {
+		u32 i = get_random_u32_below(entries);
+		u32 prand = get_random_u32_below(4);
+
+		cond_resched();
+
+		err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+		if (test_bit(i, obj_in_table)) {
+			clear_bit(i, obj_in_table);
+			if (WARN(err, "cannot remove element at slot %d", i))
+				continue;
+		} else {
+			if (WARN(err != -ENOENT, "removed non-existent element %d, error %d not %d",
+			     i, err, -ENOENT))
+				continue;
+		}
+
+		if (prand & 1) {
+			err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+			if (err == 0) {
+				if (WARN(test_and_set_bit(i, obj_in_table), "succeeded to insert same object %d", i))
+					continue;
+			} else {
+				if (WARN(!test_bit(i, obj_in_table), "failed to insert object %d", i))
+					continue;
+			}
+		}
+
+		if (prand & 2) {
+			i = get_random_u32_below(entries);
+			if (test_bit(i, obj_in_table)) {
+				err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+				WARN(err, "cannot remove element at slot %d", i);
+				if (err == 0)
+					clear_bit(i, obj_in_table);
+			} else {
+				err = rhltable_insert(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+				WARN(err, "failed to insert object %d", i);
+				if (err == 0)
+					set_bit(i, obj_in_table);
+			}
+		}
+	}
+
+	for (i = 0; i < entries; i++) {
+		cond_resched();
+		err = rhltable_remove(&rhlt, &rhl_test_objects[i].list_node, test_rht_params);
+		if (test_bit(i, obj_in_table)) {
+			if (WARN(err, "cannot remove element at slot %d", i))
+				continue;
+		} else {
+			if (WARN(err != -ENOENT, "removed non-existent element, error %d not %d",
+				 err, -ENOENT))
+				continue;
+		}
+	}
+
+	rhltable_destroy(&rhlt);
+out_free:
+	vfree(rhl_test_objects);
+	vfree(obj_in_table);
+	return ret;
+}
+
+static int __init test_rhashtable_max(struct test_obj *array,
+				      unsigned int entries)
+{
+	unsigned int i;
+	int err;
+
+	test_rht_params.max_size = roundup_pow_of_two(entries / 8);
+	err = rhashtable_init(&ht, &test_rht_params);
+	if (err)
+		return err;
+
+	for (i = 0; i < ht.max_elems; i++) {
+		struct test_obj *obj = &array[i];
+
+		obj->value.id = i * 2;
+		err = insert_retry(&ht, obj, test_rht_params);
+		if (err < 0)
+			return err;
+	}
+
+	err = insert_retry(&ht, &array[ht.max_elems], test_rht_params);
+	if (err == -E2BIG) {
+		err = 0;
+	} else {
+		pr_info("insert element %u should have failed with %d, got %d\n",
+				ht.max_elems, -E2BIG, err);
+		if (err == 0)
+			err = -1;
+	}
+
+	rhashtable_destroy(&ht);
+
+	return err;
+}
+
+static unsigned int __init print_ht(struct rhltable *rhlt)
+{
+	struct rhashtable *ht;
+	const struct bucket_table *tbl;
+	char buff[512] = "";
+	int offset = 0;
+	unsigned int i, cnt = 0;
+
+	ht = &rhlt->ht;
+	/* Take the mutex to avoid RCU warning */
+	mutex_lock(&ht->mutex);
+	tbl = rht_dereference(ht->tbl, ht);
+	for (i = 0; i < tbl->size; i++) {
+		struct rhash_head *pos, *next;
+		struct test_obj_rhl *p;
+
+		pos = rht_ptr_exclusive(tbl->buckets + i);
+		next = !rht_is_a_nulls(pos) ? rht_dereference(pos->next, ht) : NULL;
+
+		if (!rht_is_a_nulls(pos)) {
+			offset += sprintf(buff + offset, "\nbucket[%d] -> ", i);
+		}
+
+		while (!rht_is_a_nulls(pos)) {
+			struct rhlist_head *list = container_of(pos, struct rhlist_head, rhead);
+			offset += sprintf(buff + offset, "[[");
+			do {
+				pos = &list->rhead;
+				list = rht_dereference(list->next, ht);
+				p = rht_obj(ht, pos);
+
+				offset += sprintf(buff + offset, " val %d (tid=%d)%s", p->value.id, p->value.tid,
+					list? ", " : " ");
+				cnt++;
+			} while (list);
+
+			pos = next,
+			next = !rht_is_a_nulls(pos) ?
+				rht_dereference(pos->next, ht) : NULL;
+
+			offset += sprintf(buff + offset, "]]%s", !rht_is_a_nulls(pos) ? " -> " : "");
+		}
+	}
+	printk(KERN_ERR "\n---- ht: ----%s\n-------------\n", buff);
+	mutex_unlock(&ht->mutex);
+
+	return cnt;
+}
+
+static int __init test_insert_dup(struct test_obj_rhl *rhl_test_objects,
+				  int cnt, bool slow)
+{
+	struct rhltable *rhlt;
+	unsigned int i, ret;
+	const char *key;
+	int err = 0;
+
+	rhlt = kmalloc_obj(*rhlt);
+	if (WARN_ON(!rhlt))
+		return -EINVAL;
+
+	err = rhltable_init(rhlt, &test_rht_params_dup);
+	if (WARN_ON(err)) {
+		kfree(rhlt);
+		return err;
+	}
+
+	for (i = 0; i < cnt; i++) {
+		rhl_test_objects[i].value.tid = i;
+		key = rht_obj(&rhlt->ht, &rhl_test_objects[i].list_node.rhead);
+		key += test_rht_params_dup.key_offset;
+
+		if (slow) {
+			err = PTR_ERR(rhashtable_insert_slow(&rhlt->ht, key,
+							     &rhl_test_objects[i].list_node.rhead));
+			if (err == -EAGAIN)
+				err = 0;
+		} else
+			err = rhltable_insert(rhlt,
+					      &rhl_test_objects[i].list_node,
+					      test_rht_params_dup);
+		if (WARN(err, "error %d on element %d/%d (%s)\n", err, i, cnt, slow? "slow" : "fast"))
+			goto skip_print;
+	}
+
+	ret = print_ht(rhlt);
+	WARN(ret != cnt, "missing rhltable elements (%d != %d, %s)\n", ret, cnt, slow? "slow" : "fast");
+
+skip_print:
+	rhltable_destroy(rhlt);
+	kfree(rhlt);
+
+	return 0;
+}
+
+static int __init test_insert_duplicates_run(void)
+{
+	struct test_obj_rhl rhl_test_objects[3] = {};
+
+	pr_info("test inserting duplicates\n");
+
+	/* two different values that map to same bucket */
+	rhl_test_objects[0].value.id = 1;
+	rhl_test_objects[1].value.id = 21;
+
+	/* and another duplicate with same as [0] value
+	 * which will be second on the bucket list */
+	rhl_test_objects[2].value.id = rhl_test_objects[0].value.id;
+
+	test_insert_dup(rhl_test_objects, 2, false);
+	test_insert_dup(rhl_test_objects, 3, false);
+	test_insert_dup(rhl_test_objects, 2, true);
+	test_insert_dup(rhl_test_objects, 3, true);
+
+	return 0;
+}
+
+static int thread_lookup_test(struct thread_data *tdata)
+{
+	unsigned int entries = tdata->entries;
+	int i, err = 0;
+
+	for (i = 0; i < entries; i++) {
+		struct test_obj *obj;
+		struct test_obj_val key = {
+			.id = i,
+			.tid = tdata->id,
+		};
+
+		obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
+		if (obj && (tdata->objs[i].value.id == TEST_INSERT_FAIL)) {
+			pr_err("  found unexpected object %d-%d\n", key.tid, key.id);
+			err++;
+		} else if (!obj && (tdata->objs[i].value.id != TEST_INSERT_FAIL)) {
+			pr_err("  object %d-%d not found!\n", key.tid, key.id);
+			err++;
+		} else if (obj && memcmp(&obj->value, &key, sizeof(key))) {
+			pr_err("  wrong object returned (got %d-%d, expected %d-%d)\n",
+			       obj->value.tid, obj->value.id, key.tid, key.id);
+			err++;
+		}
+
+		cond_resched();
+	}
+	return err;
+}
+
+static int threadfunc(void *data)
+{
+	int i, step, err = 0, insert_retries = 0;
+	struct thread_data *tdata = data;
+
+	if (atomic_dec_and_test(&startup_count))
+		wake_up(&startup_wait);
+	if (wait_event_interruptible(startup_wait, atomic_read(&startup_count) == -1)) {
+		pr_err("  thread[%d]: interrupted\n", tdata->id);
+		goto out;
+	}
+
+	for (i = 0; i < tdata->entries; i++) {
+		tdata->objs[i].value.id = i;
+		tdata->objs[i].value.tid = tdata->id;
+		err = insert_retry(&ht, &tdata->objs[i], test_rht_params);
+		if (err > 0) {
+			insert_retries += err;
+		} else if (err) {
+			pr_err("  thread[%d]: rhashtable_insert_fast failed\n",
+			       tdata->id);
+			goto out;
+		}
+	}
+	if (insert_retries)
+		pr_info("  thread[%d]: %u insertions retried due to memory pressure\n",
+			tdata->id, insert_retries);
+
+	err = thread_lookup_test(tdata);
+	if (err) {
+		pr_err("  thread[%d]: rhashtable_lookup_test failed\n",
+		       tdata->id);
+		goto out;
+	}
+
+	for (step = 10; step > 0; step--) {
+		for (i = 0; i < tdata->entries; i += step) {
+			if (tdata->objs[i].value.id == TEST_INSERT_FAIL)
+				continue;
+			err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
+			                             test_rht_params);
+			if (err) {
+				pr_err("  thread[%d]: rhashtable_remove_fast failed\n",
+				       tdata->id);
+				goto out;
+			}
+			tdata->objs[i].value.id = TEST_INSERT_FAIL;
+
+			cond_resched();
+		}
+		err = thread_lookup_test(tdata);
+		if (err) {
+			pr_err("  thread[%d]: rhashtable_lookup_test (2) failed\n",
+			       tdata->id);
+			goto out;
+		}
+	}
+out:
+	while (!kthread_should_stop()) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+	}
+	return err;
+}
+
+static int __init test_rhashtable_next_key(void)
+{
+	struct rhashtable_params params = test_rht_params;
+	struct test_obj_val key_missing = { .id = 99999, .tid = 0 };
+	struct test_obj_val *prev_key = NULL;
+	struct rhashtable ht;
+	struct test_obj *objs, *cur;
+	int i, count = 0, err;
+	int visited_keys[8] = { 0 };
+	const int n = ARRAY_SIZE(visited_keys);
+
+	params.nelem_hint = n;
+
+	err = rhashtable_init(&ht, &params);
+	if (err)
+		return err;
+
+	objs = kcalloc(n, sizeof(*objs), GFP_KERNEL);
+	if (!objs) {
+		rhashtable_destroy(&ht);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < n; i++) {
+		objs[i].value.id = i;
+		err = rhashtable_insert_fast(&ht, &objs[i].node, params);
+		if (err)
+			goto out;
+	}
+
+	rcu_read_lock();
+
+	/* NULL prev_key: walk from the beginning, expect all n elements. */
+	while ((cur = rhashtable_next_key(&ht, prev_key))) {
+		if (IS_ERR(cur)) {
+			err = -EINVAL;
+			goto unlock;
+		}
+		count++;
+		prev_key = &cur->value;
+		visited_keys[cur->value.id] = 1;
+		if (count > n)
+			break;
+	}
+
+	if (count != n) {
+		err = -EINVAL;
+		goto unlock;
+	}
+
+	for (i = 0; i < n; i++) {
+		if (!visited_keys[i]) {
+			err = -EINVAL;
+			goto unlock;
+		}
+	}
+
+	/* Non-existing prev_key: must return ERR_PTR(-ENOENT). */
+	cur = rhashtable_next_key(&ht, &key_missing);
+	if (!IS_ERR(cur) || PTR_ERR(cur) != -ENOENT)
+		err = -EINVAL;
+
+unlock:
+	rcu_read_unlock();
+out:
+	for (i = 0; i < n; i++)
+		rhashtable_remove_fast(&ht, &objs[i].node, params);
+	kfree(objs);
+	rhashtable_destroy(&ht);
+	return err;
+}
+
+static int __init test_rht_init(void)
+{
+	unsigned int entries;
+	int i, err, started_threads = 0, failed_threads = 0;
+	u64 total_time = 0;
+	struct thread_data *tdata;
+	struct test_obj *objs;
+
+	if (parm_entries < 0)
+		parm_entries = 1;
+
+	entries = min(parm_entries, MAX_ENTRIES);
+
+	test_rht_params.automatic_shrinking = shrinking;
+	test_rht_params.max_size = max_size ? : roundup_pow_of_two(entries);
+	test_rht_params.nelem_hint = size;
+
+	objs = vzalloc(array_size(sizeof(struct test_obj),
+				  test_rht_params.max_size + 1));
+	if (!objs)
+		return -ENOMEM;
+
+	pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
+		size, max_size, shrinking);
+
+	for (i = 0; i < runs; i++) {
+		s64 time;
+
+		pr_info("Test %02d:\n", i);
+		memset(objs, 0, test_rht_params.max_size * sizeof(struct test_obj));
+
+		err = rhashtable_init(&ht, &test_rht_params);
+		if (err < 0) {
+			pr_warn("Test failed: Unable to initialize hashtable: %d\n",
+				err);
+			continue;
+		}
+
+		time = test_rhashtable(&ht, objs, entries);
+		rhashtable_destroy(&ht);
+		if (time < 0) {
+			vfree(objs);
+			pr_warn("Test failed: return code %lld\n", time);
+			return -EINVAL;
+		}
+
+		total_time += time;
+	}
+
+	pr_info("test if its possible to exceed max_size %d: %s\n",
+			test_rht_params.max_size, test_rhashtable_max(objs, entries) == 0 ?
+			"no, ok" : "YES, failed");
+	vfree(objs);
+
+	do_div(total_time, runs);
+	pr_info("Average test time: %llu\n", total_time);
+
+	test_insert_duplicates_run();
+
+	pr_info("Testing rhashtable_next_key: %s\n",
+		test_rhashtable_next_key() == 0 ? "pass" : "FAIL");
+
+	if (!tcount)
+		return 0;
+
+	pr_info("Testing concurrent rhashtable access from %d threads\n",
+	        tcount);
+	atomic_set(&startup_count, tcount);
+	tdata = vzalloc(array_size(tcount, sizeof(struct thread_data)));
+	if (!tdata)
+		return -ENOMEM;
+	objs  = vzalloc(array3_size(sizeof(struct test_obj), tcount, entries));
+	if (!objs) {
+		vfree(tdata);
+		return -ENOMEM;
+	}
+
+	test_rht_params.max_size = max_size ? :
+	                           roundup_pow_of_two(tcount * entries);
+	err = rhashtable_init(&ht, &test_rht_params);
+	if (err < 0) {
+		pr_warn("Test failed: Unable to initialize hashtable: %d\n",
+			err);
+		vfree(tdata);
+		vfree(objs);
+		return -EINVAL;
+	}
+	for (i = 0; i < tcount; i++) {
+		tdata[i].id = i;
+		tdata[i].entries = entries;
+		tdata[i].objs = objs + i * entries;
+		tdata[i].task = kthread_run(threadfunc, &tdata[i],
+		                            "rhashtable_thrad[%d]", i);
+		if (IS_ERR(tdata[i].task)) {
+			pr_err(" kthread_run failed for thread %d\n", i);
+			atomic_dec(&startup_count);
+		} else {
+			started_threads++;
+		}
+	}
+	if (wait_event_interruptible(startup_wait, atomic_read(&startup_count) == 0))
+		pr_err("  wait_event interruptible failed\n");
+	/* count is 0 now, set it to -1 and wake up all threads together */
+	atomic_dec(&startup_count);
+	wake_up_all(&startup_wait);
+	for (i = 0; i < tcount; i++) {
+		if (IS_ERR(tdata[i].task))
+			continue;
+		if ((err = kthread_stop(tdata[i].task))) {
+			pr_warn("Test failed: thread %d returned: %d\n",
+			        i, err);
+			failed_threads++;
+		}
+	}
+	rhashtable_destroy(&ht);
+	vfree(tdata);
+	vfree(objs);
+
+	/*
+	 * rhltable_remove is very expensive, default values can cause test
+	 * to run for 2 minutes or more,  use a smaller number instead.
+	 */
+	err = test_rhltable(entries / 16);
+	pr_info("Started %d threads, %d failed, rhltable test returns %d\n",
+	        started_threads, failed_threads, err);
+	return 0;
+}
+
+static void __exit test_rht_exit(void)
+{
+}
+
+module_init(test_rht_init);
+module_exit(test_rht_exit);
+
+MODULE_DESCRIPTION("Resizable, Scalable, Concurrent Hash Table test module");
+MODULE_LICENSE("GPL v2");